1. Field of the Invention
This invention relates to internal-combustion, reciprocating-piston engines and combustion processes used therein and more specifically, this invention relates to internal-combustion, reciprocating-piston engines which use a sidewall combustion chamber and a displacer-piston for improving output power and efficiency.
2. Description of Prior Art
Combustion normally occurs in common reciprocating-piston, internal combustion engines when the piston reaches the highest point in the cylinder in order to take advantage of maximum compression of the fuel/air mixture at the time of ignition. At that point, however, the piston's connecting rod is nearly vertically aligned with the cylinder and very little of the large force acting downward on the piston crown immediately after ignition actually works to rotate the crankshaft. Most of the tremendous force from the burning fuel-air mixture is momentarily acting in a manner that places a heavy burden on the crankshaft and its bearings. More specifically, a force equal to the cosine of the crankshaft's rotational angle after top-dead-center multiplied by the force acting downward on the piston does little to rotate the crankshaft, but instead acts to drive the crankshaft out of the engine. A relatively small force equal to the sine of the crankshaft's rotational angle after top-dead-center multiplied by the force acting downward on the piston actually works tangentially to rotate the crankshaft immediately after ignition of the fuel-air mixture. Ignition of the fuel-air mixture at top-dead-center in any reciprocating-piston, internal-combustion engine seems to be an inherent disadvantage of such engines that results in relatively low output power and efficiency.
Negre discloses in U.S. Pat. No. 6,094,915 (Negre, et al., 2000) what would commonly be considered a split-cycle internal combustion automobile engine where the compression, combustion, and expansion phases of the engine-cycle are done in three separate portions of the engine. Compressed air, supplied by either an external source or a compressor in another location of the vehicle, is mixed with fuel and then fed to a combustion chamber where the fuel/air mixture is ignited. The ignited mixture is then fed into an expansion chamber existing between a main piston and a second piston that follows the main piston down the expansion cylinder, in order to provide a minimum volume to produce “an optimum expansion mean tangential force” to the main piston. Negre failed to disclose, however, a method of using a single piston moving in a cylinder to compress air or another gas needed for the combustion process, and then subsequently using the same piston in the same cylinder for the expansion or power phase of the engine-cycle. More critically, Negre failed to disclose, and surely did not contemplate, a method to allow a piston in a cylinder to compress air to be used for the combustion process and then supply the ignited high-pressure mixture of fuel and gases back to the same cylinder, but directly into an expansion chamber formed between the same piston in the same cylinder, and a second piston that follows the first piston down the cylinder, in order to provide a minimum volume to produce “an optimum expansion mean tangential force” to the main piston. Such a method would obviously require fewer parts and would be much simpler in design. On the contrary, Negre would instead have the compression of the air or another gas done by either an entire separate air-compressor in the vehicle or by an air-compressor at a “filling” station.
There is a need then, for a method of using the same piston and cylinder combination for both compression and expansion phases which would then reduce the number of engine components to complete the same processes as accomplished by the Negre engine. A reduced number of engine components would in turn reduce the complexity, weight, and cost of building the engine. When used in an automobile, reduced engine weight means less fuel is required and less energy is needed to move the vehicle down the road which means less pollution of the environment occurs since less fuel is needed to power the automobile. Negre failed to anticipate or expect such results even though the intent of that invention is to reduce pollution and save fuel! So, Negre failed to disclose an engine that is not of the separate-cylinder, split-cycle type where a piston moves in a cylinder compressing a volume of air or another gas for use in the combustion process and where the ignited mixture is used to drive the same piston in the same cylinder during the expansion or power phase of the engine-cycle. Methods such as the one just described and which was previously-unanticipated, yet more-promising, are contrary to the commonly-held and seemingly growing belief that a complicated engine of the separate-cylinder, split-cycle type is required to accomplish the task of delaying ignition or prolonging the combustion process (or “burn”) until the crankshaft is in a better position to receive the energy released from the combustion of a fuel and air mixture. Split-cycle engines using separate or multiple cylinders for different engine-phases have been in existence for a very long time and have not proven feasible on a commercial basis for one reason or another. Moreover, it will be shown that such a belief and requirement is simply not substantiated in real practice because simpler engines with fewer parts can be built to accomplish the same objectives. A much simpler and effective internal combustion reciprocating-piston engine is therefore needed that operates on the Otto cycle and is an improvement over the Negre engine which can delay ignition and the combustion process until the piston, crankshaft, and connecting-rod are in an optimum position at or past top-dead-center to receive energy or forces. More specifically, an engine and method are needed where compressed air, or a mixture of compressed air and fuel, is taken from a cylinder while a piston is at top-dead-center in the cylinder for achieving maximum compression, then after igniting the fuel and air mixture, subsequently re-introducing the burning fuel/air mixture into the same cylinder at a more optimum time and location within the cylinder for driving the piston in the cylinder more efficiently and with greater output power.
The concept described and disclosed in the Negre engine where a secondary piston follows or accompanies a main piston over part of its downward or power stroke in order to provide a minimum volume to produce “an optimum expansion mean tangential force” to the main piston is not a new concept since it has been successfully marketed and used by a major engine manufacturer for many years. An article from “Diesel-Electric Locomotive” (Foell and Thompson, 1946) describes the process as used in the Fairbanks-Morse 38D8 two-stroke opposed-piston engine as follows: “The underlying principle of the two-stroke cycle opposed-piston Diesel is the use of a plain open-ended cylinder in which combustion takes place in the center of its length between two pistons which move away from each other. The pistons are utilized to uncover the exhaust and air-inlet ports, thus eliminating the use of valves. The pistons controlling the air-inlet ports are connected to the upper crankshaft, while those controlling the exhaust ports are connected to the lower crankshaft. The two shafts are mechanically connected by a vertical shaft and bevel gears, with the lower shaft (exhaust end) being set 12 degrees ahead of the upper shaft (inlet end) . . . . It is also obvious that when the upper piston is at inner dead center, the lower one has completed 12 degrees of its power stroke. This causes the lower piston to receive the greater part of the expansion work, at full engine load, with the result that about 72 percent of the total power is delivered by the lower crankshaft. The remaining power is delivered to the upper crankshaft where it is partially absorbed in driving the blower, leaving only a relatively small amount of power to be transmitted through the vertical gear drive to the lower crankshaft, which is connected to the driven machine . . . The 12 degrees by which the exhaust piston “leads” the intake piston permits a more advantageous port timing, and also allows for a limited amount of “ram” effect which further contributes to the operating economy.” As complicated as the Fairbanks-Morse engine is—with two separate crankshafts—the process used in that engine to delay combustion until one piston and its crankshaft are in a more optimum position to receive energy and forces has proven over the years to be quite feasible. But again, the Fairbanks Morse engine is complicated and requires a large number of expensive, heavy parts. The Negre engine, however, would need an entire separate air-compressor or filling-station to accomplish the same task! Again, an engine comprised of fewer parts and with less complexity than either the Fairbanks-Morse 38D8 engine or the Negre engine is needed for increasing effectiveness and efficiency.
Scuderi first discloses in U.S. Pat. No. 6,543,225 (Scuderi, 2003) a gas passage in a split-cycle engine that exists between a first cylinder and a second cylinder where the first piston in the first cylinder is used to compress air or another gas while the combustion process and expansion of the ignited fuel/air mixture is accomplished in the second cylinder by the moving second piston. This process allows extra compressed air to be introduced into the second cylinder in order to prolong the “burn” until the second piston and the common crankshaft are in positions at or after top-dead-center to receive energy (or forces) in a better manner. In a second U.S. Pat. No. 6,397,579 (Negre, 2002), Negre discloses a split-cycle engine (herein referred to as the second Negre engine) that has a separate, independent combustion chamber located between a first cylinder used for compressing air (or another gas) and a second cylinder used for gas-expansion or the power-stroke. The process in the second Negre engine is similar to the process in the Scuderi engine since both seem to accomplish the same task of prolonging the “burn” with additional injected compressed-air from the first cylinder so the expansion piston and common crankshaft are in more optimum positions to receive energy. It's important to notice, however, that both the gas passage in the Scuderi engine and the separate, independent combustion chamber in the second Negre engine receive compressed air, or another gas, from one cylinder and re-inject the ignited fuel/air mixture into a second and entirely different cylinder for use in the expansion and the power-stroke phases of the engine-cycle. A separate, independent combustion chamber as presented in both Negre engines can also receive compressed-air or another gas from a separate air-compressor or storage tank located somewhere in the vehicle before the burning fuel/air mixture is later introduced into an entirely separate expansion chamber. There is currently no engine design in use today, however, with a separate, independent combustion chamber that receives air or gas from one cylinder and re-injects a burning, ignited fuel/air mixture back into the same cylinder from where it was originally taken.
A very serious problem and disadvantage with both Negre engines and the Scuderi engine will become more obvious and apparent once those engines are eventually built and tested or if they're ever used on a wide scale. The gas-expansion and power-stroke cylinders in those engines apparently are never cooled by fresh-air from an intake-valve which means an external source of cool air will be required for cooling purposes, or else special materials will be needed for operating in extremely high heat-stress conditions. Such an inherent and detrimental design-flaw will undoubtedly increase the cost of producing the Negre and Scuderi engines and will decrease both the performance and efficiency of those engines. This brings up operability and effectiveness questions regarding separate-cylinder, split-cycle type engines in general, since every design currently available for inspection seems to include the same cooling problem.
There is no engine or method available for use today that contains a separate gas passage or separate, independent combustion chamber that receives compressed air, or another gas, from one cylinder and re-injects the ignited fuel/air mixture at a much higher pressure into the exact same cylinder, except at a different location from where the compressed gas was originally taken from. Furthermore, there is certainly no engine or method currently available, of the split-cycle type or otherwise, with a separate combustion chamber that receives compressed air from one location in a cylinder and then subsequently re-introduces high-pressure combustion gases back into the same cylinder directly into an expansion chamber formed between a main piston in the cylinder and a second piston which follows the main piston part-way “down” the same cylinder in order to minimize volume and enhance the expansion process for maximizing output power and overall efficiency.